This invention generally relates to a tandem axle suspension assembly, and more specifically to a walking beam tandem axle suspension assembly.
Typically, vehicles such as cargo trailers include a mechanical steel leaf spring for suspending an axle from a vehicle frame. The steel leaf spring suspension requires little maintenance and provides favorable loading dock performance. The favorable dock performance results from a relatively small amount of vertical displacement between loaded and unloaded conditions of the leaf spring suspension. However, the leaf spring suspension may provide relatively harsh ride characteristics during unloaded or lightly loaded conditions.
Another trailer suspension utilizes air springs for each axle. The air springs provide favorable ride characteristics regardless of the load on the trailer. Further, specific ride characteristics can be tailored to a specific load and desired handling characteristics.
Disadvantageously, an air suspension system may be more expensive than a comparable leaf spring suspension. Air spring suspension systems may also not provide optimal loading dock performance due to height variations between loaded and unloaded conditions. In some instances, conventional air spring suspension systems utilize mechanical add on devices such as an adjustable stop inserted between the trailer frame and the suspension to limit movement relative to a loading dock. Other devices include manually operated jacks that support the trailer at a fixed height. Such devices typically require manual operation before, during and after the loading process. As appreciated, these mechanical add on devices increase weight, expense, and maintenance requirements.
Accordingly, it is desirable to develop an air spring suspension system with favorable loading dock performance without sacrificing favorable ride characteristics.